VM: Circ supply should be constant per epoch

[arajasek]

The current behaviour violates the spec (see here)

[jennijuju]

why do you piss ci off

[codecov]

Codecov Report

Merging #7811 (1f04cc1) into master (690be5b) will increase coverage by 0.05%.
The diff coverage is 80.00%.

@@            Coverage Diff             @@
##           master    #7811      +/-   ##
==========================================
+ Coverage   39.53%   39.58%   +0.05%     
==========================================
  Files         653      653              
  Lines       69925    69932       +7     
==========================================
+ Hits        27644    27685      +41     
+ Misses      37544    37501      -43     
- Partials     4737     4746       +9     

Impacted Files	Coverage Δ
chain/vm/vm.go	63.31% <71.42%> (-0.03%)	⬇️
chain/gen/genesis/genesis.go	46.74% <100.00%> (+0.33%)	⬆️
chain/events/message_cache.go	87.50% <0.00%> (-12.50%)	⬇️
markets/loggers/loggers.go	89.28% <0.00%> (-10.72%)	⬇️
chain/sub/incoming.go	54.43% <0.00%> (-10.13%)	⬇️
chain/stmgr/execute.go	86.95% <0.00%> (-4.35%)	⬇️
chain/events/events_called.go	83.90% <0.00%> (-1.96%)	⬇️
chain/stmgr/searchwait.go	66.02% <0.00%> (-1.29%)	⬇️
node/modules/lp2p/pubsub.go	59.39% <0.00%> (-1.02%)	⬇️
markets/storageadapter/dealpublisher.go	82.03% <0.00%> (-0.49%)	⬇️
... and 22 more

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